1. Field of the Invention
The present invention relates generally to a sheet-feeding apparatus, and more particularly, to a sheet-feeding apparatus with a paper stopper.
2. The Related Art
Office machine, such as printers, scanners, copiers and the like, generally includes a sheet-feeding apparatus for feeding papers into the office machine. The sheet-feeding apparatus is generally provided with a stopper mechanism. When the sheets are placed on a sheet-supplying tray of the office machine, the stopper mechanism protrudes into the sheet entrance or path to restrict the leading edge of the sheet to prevent the sheet from entering into the machine. When the sheet operation starts, the stopper mechanism retracts from the sheet entrance to allow the sheet to advance into the machine.
FIG. 18 is a cross-sectional view illustrating a conventional sheet-feeding apparatus. The sheet-feeding apparatus comprises a preliminary feeding roller unit 92 for taking a sheet from a sheet-placing unit 96. A feeding roller unit 93 is located at downstream of the preliminary feeding roller unit 92 in the sheet-transferring direction.
The feeding roller unit 93 has a supporting shaft 93a to which a lever 97 is rotationally attached. A lever 97 has a swinging end to which a supporting shaft 92a of the preliminary feeding roller unit 92 is rotationally attached. A rotational force is given to the feeding roller unit 93 from a driving motor (not shown) and the rotational force is also transmitted to the preliminary feeding roller unit 92 through a gear mechanism (not shown).
A sheet stopper 95 is disposed between the preliminary feeding roller unit 92 and the feeding roller unit 93. The sheet stopper 95 swings. A locking mechanism 98 for locking the swinging of the sheet stopper 95 is located at the upside end of the sheet stopper 95. This locking mechanism 98 has a driving means, such as a solenoid, for locking and releasing the sheet stopper 95.
When the solenoid is energized, the sheet stopper 95 swings and allows the sheet to be transferred to the feeding roller unit 93. When the solenoid is not energized, the sheet stopper 95 is locked by the locking mechanism 98 to prevent the sheet from being transferred to the feeding roller unit 93.
When the sheet is set, the preliminary feeding roller unit 92 is raised and the sheet stopper 95 is locked in order to prevent the sheet from being transferred to the feeding roller unit 93.
When the sheet stopper 95 is released, the sheet enters into the sheet-feeding passage while the sheet stopper 95 is swinged by the sheet.
Such design further requires an electric system to supply driving power to the driving motor. The gear mechanism is also provided for transferring the rotational force from the driving motor to the preliminary feeding roller unit 92 and the feeding roller unit 93. This design complicates the structure of the apparatus and increases the cost of manufacture.